A steering system of a motor vehicle serves in a known fashion to transmit rotational movement of a steering wheel (i.e., a steering element) to steer wheels of the motor vehicle. To this end, the steering wheel can be connected in a rotationally fixed fashion to a pinion of a toothed rack steering gear (e.g., a rack and pinion type steering system) by means of a steering shaft. The toothed rack is consequently displaced axially and acts on one or more wheels of the motor vehicle (e.g., via a steering linkage that is connected to one or more wheel carriers (e.g., hubs)) for enabling pivoting (i.e., steering) of the one or more wheels.
In particular, in the case of an electrically driven power steering systems (e.g., an electric power assisted steering (EPAS) system), very high torques can need to be transmitted between the pinion and the toothed rack by the toothed rack steering gear. This same situation can, of course, also apply to a hydraulic power assist steering (HPAS) system or mixed forms of steering system such as for example an electric hydraulic power assist steering (EHPAS) system. The torques which have to be transmitted between pinion and toothed rack usually increase as the steering lock increases, i.e. as the toothed rack is increasingly axially displaced from the center position in the direction of the axial end positions of the toothed rack (i.e., the steering effort increases as a function of displacement of the toothed rack).
Motor vehicles are increasingly being equipped with what are referred to as driving assistance systems or control elements. An example of such a driving assistance system is one that provides lane keeping assistance (i.e., a lane departure warning system) by helping a driver to maintaining the motor vehicle within a given lane of a roadway over which the motor vehicle is travelling. For example, the driver could be informed that the vehicle threatens to leave the lane by one or more corresponding control elements such as vibrating of the steering wheel.
It is possible with such driving assistance systems that they also influence steering provided by the steering system itself such as by, for example, steering virtually independently or automatically. In this case, the intervention can, however, be such that as far as possible the driver does not notice this. Of course, steering corrections by driving assistance systems are desirable. For example, if the driver were to take both hands off the steering wheel (i.e., a steering element which can be operated manually) during an instance of assisted steering functionality or if the driver were to only steer loosely with its his fingers during an instance of assisted steering functionality (i.e., a virtually hands-free driving situation), the driving assistance system would nevertheless carry out the respectively detected steering corrections (i.e., would steer independently). Such independent steering or such independent steering reactions to detected requests on the part of the driving assistance systems (e.g., a driving assistance system that provides for autopilot type driving assistance functionality) would go beyond what is referred to in the industry as the “steer-by-wire”, which is an example of purely electrical steering. However, such autopilot types of driving assistance functionality are not permitted in certain currently valid motor vehicle operations regulations that authorize the use of motor vehicles for road traffic. Germany is one example of a country with current motor vehicle operations regulations that do not permit autopilot types of driving assistance functionality.
Therefore, detecting a hands-free driving situation in a motor vehicle would be beneficial advantageous, desirable and useful.